Genetic variation in Echinacea angustifolia along a climatic gradient (original) (raw)
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Conservation Genetics, 2008
PETERS, MELINDA DEAN. Genetic analyses of the federally endangered Echinacea laevigata using amplified fragment length polymorphisms (AFLP)-Inferences in population genetic structure and mating system. (Under the direction of Dr. Qiu-Yun (Jenny) Xiang) Echinacea laevigata is a federally endangered species and a close relative of the medicinally important E. purpurea. It was listed by the US Fish and Wildlife Service on October 8, 1992. The species has 24 recognized populations restricted to four states (VA, NC, SC, GA). Since prior knowledge of the mating system is limited, an estimation of outcrossing will provide information if gene flow can occur across the range of the population. Information about the genetic structure and mating system will guide future management efforts of this species. To determine the population structure and outcrossing rate across the range of the species, I conducted AFLP analysis using four primer combinations for 22 populations. The genetic diversity of this species was found to be high based on the level of polymorphic loci (200 of 210 loci; 95.24%) and Nei's gene diversity (ranging from 0.1398 to 0.2606; overall 0.2611). There was significant population genetic differentiation (G ST of 0.2941), suggesting possible adaptation to local environments. Results from AMOVA analysis suggest that a majority of the genetic variance is attributed to variation within populations (70.26%). These results are congruent with a previous allozyme study that examined the genetic makeup of 11 of the 24 populations, excluding the Georgia populations. An isolation by distance analysis indicated that genetic differentiation among populations is a function of geographic distance, although long-distance gene dispersal (LDGF) between some populations was suggested based on population relationships from phylogenetic analysis. An estimate of the outcrossing rate based on genotypes of progenies from six of the 22 populations using a method of multilocus estimate ranged from 0.833-1.2, where 1.2 is considered complete outcrossing, suggesting that the species is predominantly outcrossing. The data provide an estimate of genetic diversity and structure, which can be used to assist in the conservation of the species.
2007
The four native Missouri taxa of Echinacea were used as a model to test the predictive value of herbarium data with regard to present-day distribution. Specimens with label data considered potentially adequate to relocate the population were databased and the sites in question were visited. Most of the historical populations were not relocated, although a greater percentage of those collected post-1980 were found to still exist. Time since collection significantly affected the probability of relocation of E. purpurea and E. pallida var. pallida, the two native taxa commonly harvested for medicinal products. The collection rate for E. pallida var. pallida remained high over time. However, the collection rate for E. purpurea has been much reduced in recent decades. Few of the historical populations were relocated, and located populations on unprotected public land were very small, perhaps indicating that habitat loss or human activity is causing a decline in Missouri populations of E. purpurea.
The use of RAPDs for assessment of identity, diversity, and quality of Echinacea
2002
The genus Echinacea, Asteraceae, is comprised of nine species, which are perennial herbs indigenous to North America and which have been traditionally used as medicinal plants for centuries. Three Echinacea species, E. angustifolia DC var. angustifolia, E. purpurea (L.) Moench, and E. pallida (Nutt.) Nutt., are currently being traded internationally in the natural products market. Echinacea products constitute a significant portion of this growing, multi-billion dollar industry. Echinacea is considered of value as a nonspecific immune stimulant; the pharmacological activity of Echinacea extracts has been widely studied with over 350 published studies to date (Briskin 2000) together providing strong evidence for an immune modulating activity of these extracts. The increasing popularity of Echinacea products has led to expansion in wildcrafting and commercial cultivation to meet the growing demand for plant material. Commercial supplies of E. purpurea are obtained from cultivated sources; E. angustifolia and E. pallida have until recently been supplied largely from indigenous habitats in the United States (Foster 1993). The threat to the genetic diversity present in wild populations due to indiscriminant overharvesting and the need for preservation of these genetic resources creates an incentive for the determination of the genetic variability present within these three species. The quality of botanical materials used in the manufacture of natural products has also been of concern with Echinacea products. Parthenium integrifolium is a common prairie perennial with a root morphology similar to that of E. angustifolia; roots of this plant have been a frequent adulterant of dried roots of E. angustifolia. DNA fingerprinting techniques such as random amplified polymorphic DNA (RAPD) (Williams et al. 1990) permit the identification of taxa and the determination of phylogenetic relationships and intraspecific diversity at a molecular genetic level. The use of such techniques for germplasm characterization facilitates the conservation and utilization of plant genetic resources, permitting the identification of unique accessions or sources of genetically diverse germplasm. The ability of this method to distinguish between taxa also has useful implications in botanical quality analysis. This study used RAPD markers to determine the genetic relationships of the three Echinacea species of commercial interest, to evaluate the level of diversity present within germplasm of each of the three species, and to compare accessions of each species available from different sources including the USDA National Plant Germplasm System and commercial sources. RAPD markers were also identified that are capable of distinguishing the presence of Parthenium integrifolium L., an adulterant of E. angustifolia, in DNA samples extracted from combined tissue of the two species. The 17 species-specific markers generated for the three Echinacea species in this study may also be useful in the identification of Echinacea species included in samples of botanical material or finished products. EXPERIMENTAL PROCEDURES Plant Material A total of 19 accessions of Echinacea were used in this study, including one outgroup E. atrorubens Nutt. accession. A complete list of the accessions and their sources is available (Kapteyn et al. 2002). Seed from each accession was germinated after stratification with (2-chloroethyl) phosphonic acid (Sari et al. 1999), and plants of each accession were grown in a greenhouse at
The Study of Several Genotypes of Echinacea Purpurea (L.) Moench
Research aimed at the evaluation and selection of biological material, genetically valuable for several genotypes of Echinacea purpurea (L.) Moench. The experiment, that took place during the years 2008 şi 2009, aimed the phenological study and the content of active principles in several genotypes of Echinacea purpurea (L.) Moench received from 8 different locations in Europe and of a population from Cluj (acclimated since 1982 in our university). All the tested plants have been multiplied by means of seedlings. Among the investigated genotypes during both consecutive years, under the climatic conditions from Cluj – Napoca, the earliest (regarding the vegetation period) were: Porrentry (Switzerland) and the population from Cluj, related to the control variants (the average of the experimental plot).The aerial parts had a major contribution to the whole plant weight. It was noticed that, during each year of experience, the genotypes Warsaw-Poland, Műnchen-Germany, Siena-Italy, and Je...
Journal of Biogeography, 2017
Aim: We sought to determine if the present fragmentary distribution of the giant columnar cactus Echinopsis terscheckii in tropical drylands is a relict of a previously more widespread range during cold and dry phases of the Last Glacial Maximum (LGM). Location: Tropical and subtropical dry ecotonal areas of northern and central Andes of Argentina. Methods: We combined ecological niche models (ENM) with molecular polymorphisms of isozymes and DNA sequences. We collected samples from 30 individuals at 24 locations for genetic analysis covering a wide range of environmental conditions. We sequenced the nuclear ITS and three non-coding regions of the chloroplast DNA and we resolved 15 isozyme loci. Potential distribution was modelled using 88 E. terscheckii presence training records and a reduced set of 10 modern bioclimatic variables. LGM and the Mid-Holocene distributions were derived by projecting bioclimatic data under present to past environmental conditions according to CCSM4 and MIROC-ESM Global Climate Models. Results: We detected high isozyme diversity towards the south. The multivariate cluster analysis yielded two groups of populations that were geographically concordant with the DNA haplotypes located north and south of a divide at 27°S. Distribution models show range expansion during the LGM in two north and south areas separated by a gap of low suitability at 27°S. Suitable areas in the south were close to current populations, while in the north, populations survived in more disjunct locations that probably suffered from founder effects. In contrast, Mid-Holocene bioclimatic conditions were relatively unsuitable in the south. Main conclusions: Our results suggest that the divergence of north and south groups of E. terscheckii populations reflect long-lasting persistence through climatic cycles that were reinforced by the presence of an orogenic divide at mid-latitudes. Latitudinally divergent groups of populations should be treated as distinct evolutionary significant units that deserve independent conservation actions. Increased genetic diversity and inbreeding towards the south may guide setting up priorities for the long-term protection of a dominant element of drylands as E. terscheckii.
Journal of Heredity
Species inhabiting drylands commonly depend on the surrounding vegetation for recruitment under stress, while competition may affect populations in moister environments. Our objective was to analyze how different climates and vegetation affect the fine-scale spatial genetic structure (SGS) of the columnar cactus Echinopsis terscheckii. At 4 sites, we estimated vegetation cover by digitized patches and the normalized difference vegetation index (NDVI). We mapped 30 individuals per population and collected tissue for isozyme electrophoresis using 15 putative loci. Spatial autocorrelation between all possible genotype pairs and the number of genetically homogeneous groups and families were calculated for each population. Greater cover (66%) and average NDVI values were detected in the most humid habitat that consisted of fewer, larger, and more dispersed vegetation patches. All populations were genetically diverse and showed significant SGS. Positive correlations were found between the distance at which maximum autocorrelation and kinship values were reached and vegetation area and patch size. Also higher NDVI values were associated with lower number of patches. Populations exposed to higher precipitation and vegetation cover consisted of sparse individuals that clustered at larger distances whereas vegetation patches in arid climates produced groups of closely related genotypes at small distances. These results support the stress-gradient genetic hypothesis. Under water stress, facilitation promotes establishment underneath patchy vegetation resulting in fine-scale family structure. In moister xerophilous forests, competition for resources, that is, light, results in sparse individuals and thus coarse-scale neighborhoods. This information can guide conservation and/or restoration efforts, such as the spatial scale to be considered in germplasm collection.
Isozyme Variation in Echinocereus engelmannii var. munzii (Cacteceae)
Conservation Biology, 1996
Assessing the degree of evolutionary differentiation between a rare taxon and its relatives is critical from a biological perspective. Because funding and time are limited, conservation biologists need to set maintainance of truly unique pieces of biodiverstty as a higher priority than maintenance of interesting populations of widespread species. Although many factors go into setting priorities, thorough assessment of evolutionary distinctiveness based on multiple lines of evidence is the most basic. We used isozyme characters to assess the distinctiveness of a purportedly rare taxon, Echinocereus engelmannii var. munzii (Munz's hedgehog cactus), from other common varieties of the same species. We sampled at least 15 individuals from one population in each of the three mountain ranges where E. e. var. munzii is present within the United States plus three corresponding desert populations of a more common variety. To test for cUnal variation between mountain and desert populations, we sampled three elevationally intermediate populations in the San Bernardino Mountains. We recognized a total of 104 band patterns for nine enzyme systems. All nine enzyme systems yielded polymorphic zymograms. Although we found substantial intrapopulation variability, no significant isozymic differentiation was apparent among any of the sampled populations. Lack of such differentiation implies that the effects of selection or drift have not been felt or detected in these populations. In terms of these enzyme systems Echinocereus engelmannii var. munzii is not distinct from other members of the species. Although there is no evidence of isozymic distinction, morphological evidence should be included in any decisions to submerge this taxon.